Rock sampling method



Dec. 13, 3938. v. v. VACQUIER 'ROCK sAMPLlNG METHOD.

Filed June 6, 1938 FLUEN T CEMEN wlTN MAG. PARTCLES Patented-pee." 13, 193e 2,140,097-,

.UNITED STATES PATENT OFFICE Victor V. Vacqnier, Oakmont, Pa., assigner to Gulf Research & Development Company, Pittsy bnrgh, Pa., a corporation of Delaware Application June 6, 1938, Serial No. 212,142

' 'i claims. (a. s55-72) This invention or discovery relates to improve. body of magneticallysusceptible particles in a ments in rock sampling methods; and it comtemporarily free or non-oriented state, letting the prises av method of taking rock core vsamples in particles become oriented solely under the inucore drilling, including the steps of introducing ence of the earths magnetic eld and xed in adjacent the rock to be sampled a charge of magsuch orientation, and taking a core sample con- 5: netically susceptible particles in atemporary containing the fixed particles. The removed core l dition such as to be capable o! polar orientation has remanent magnetism; it is thereby magunder the influence of the earth's magnetic iield, netically marked, so to speak. The particles are allowing such orientation to take place and to 'bearranged parallel to the direction of the earths come xed, and removing a core sample of the magnetic eld for the locality, and by determinl0 v rock containing the oriented charge, whereby ing the constants of polarity of the particles `on the original orientation of the rock before rethe core with the aid of a sensitive inagnetometer moval can be determined; all as morefully hereused in a known way; the original orientation of inafter set forth and as claimed, the core in the earth can be found, and true dip In studying underground geological formations and strike determined. Thus a single curing sufl5 it is desirable to'secure infomation as to the flces to determine the direction of dip o! the character of the rock at various underground rocks adjacent the'well bore. levels, and also as to the dip and strike of the' The iventien may be Carried Out in any One rock masses if they occur in'strata (i. e. denite of several dierent ways. For example, after layers or beds). Infomation as to the dip and drilling has proceeded 130 the desired depth in 8 20 strike of buried rock strata, at several points over known way, I sometimes drill a bore somewhat an area, shows whether the strata are horizontal smaller than the core subsequently t0 be taken or are iaulted or warped into anticlines, synand pour into the small bore a fluid suspension clines, etc. v 'l oi quick setting cement containing m'agnetized.l Core drilling is awell known method of Ainvesparticles of magnetite or other suitable ierro- 25 tigating subsurface geology. It is sometimes car-V magnetic particles in suspension. While the ceried out incidentally to well drilling, and somement remains liquid the particles 0f manetite times as an independent procedure. In core drillorient themselves in the direction of the earth's .ing, a tubular bit is used.` arranged to drill out magnetic iield. The cement is then permitted to 3o and break oiland remove a cylindrical core of set in the formation whereby the magnetic par- 30.

rock. Examination ot the core reveals the char. ticles are xed or cemented to the core and the ac ter of the rock at the level at which the samcore is thereby given a residual or remanent magple was taken, butV ordinarily yields no' iniormanetism in the direction o! the earth's eld. After' tion as to the direction oi dip of the rock. Cores the cement has set, a core specimen is taken in 35 of sedimentaryvrock often show dipping bedding the usual manner( and brought to the surface, 3:5/Y

planes quite clearly, but there has been no very where it is oriented as described above.

convenient way of ascertaining what was the Another way in which the invention may be original orientation of the rock core in the earth carried out is to embed in the rock before sambefore removal, because the drill twists around .ming a ferro-magnetic substance, raise the tem;

40 during removal and moreover because the drill pratl-e f the substance have its Cm-1e pom 40 may not have been exactly vertical when the which is the temperauue (varying with different 'sample was taken- Thus while the removed core materials) at which it mees its magnetic propshows dip, there is no direct way of telling the emes, -and then permit the suman, to 001,

direction the 'dip takes in the earth. Takinga plurality of core s'ampliover a small area makes whereupon it acquires remanent magnetization in 45 the direction of the vearths iield. .Such a magpossible such determination, by revealing the Y I same stratum of rock lying at different levels in neue substance. may befxed m the, core En the different wells,- but this expedient is costly. to heating it am .the Curie mint or fm l According to the' present invention there is b-e heatedmasumciently high tempmwe Pm" provided a simple and efl'ective way or taking t0. intlf'oduction to the 1`e For instance a 50 core samplesvin which-the original orientation of Slug 0! material such as a mixture 0f ,cobalt and.

the core priorto removal can be determined from i1'0n Oxides may be heated above 500 c" at which an examination of the core at the surface of thev temperature itloees its magnetic properties and earth. This is achieved by introducing into the subsequently the slug may be med-into the rock g 55, rock, before a core sample thereof isremoyed, a as a bullet in a heated condition. Certain other ferro-magnetic substances have lower "Curie points and are sometimes more convenient.

For the purpose of this invention a iiuid suspension of tiny ferro-magnetic particles behaves in a manner quite analogous to the behavior of a mass of a ferro-magnetic substance which is heated above its Curie point. 'In either the fluid suspension or the heated mass there is a body of ferromagnetic particles in such a state as to be susceptible of polar orientation under the inuence of the earths magnetic iield. A ferro-magnetic mass is considered to bemade up of an aggregation of particles each of which behaves as an elemental magnet or dipole. At temperatures above the Curie point it is believed the `movement of the dipoles in the mass is quite random, hence the individualA magnetic particles in the mass are not oriented and do not exert a cumulative polar effect. As the mass cools, `the free energy and random movement of the dipoles becomes less,

the elemental magnetic particles then becoming oriented in (alined with) the direction of the earths eld when other magnetic forces are absent. When oriented, these particles exert a cumulative polar eiect. As long as the mass remains cool and otherwise magnetically undisturbed the mass of particles retain this orientation and their cumulative enect may be measured to determine the direction of the polar forces with respect to the mass.

With regard to a fluid suspension of finely divided ferro-magnetic particles, each particle is to all intents and purposes a dipole of such minute physical dimensions and mass as to be readily susceptible of orientation when subjected to magnetic forces. While suspended in a uid, there is-relatively slight resistance to such orientation. Therefore, when a iluid suspension of such particles is adapted to set on standing and is left at rest the particles gradually orient themselves in the direction of the earths magnetic field and, as the suspension sets, the particles become xed in this oriented position where their cumulative effect may be measured to determine `the direction of the polar forces with respect to the mass. Even though the orientation may not be complete, enough polarity is imparted for the present purposes.

In the accompanying drawing I have shown, more or less diagranmiatically, certain apparatus useful in carrying out the present invention in some of its specific embodiments and a typical core sample taken by the method of the present invention. l,

In the showing,

Fig. 1 is a longitudinal sectional view, partly broken away, of a conventional rotary core drill with a retractable inner barrel particularly adapted for the carrying out of the invention:

Fig. 2 shows a replaceable coring bit adapted to replace the small central drill shown in Fig. 1;

Fig. 3 shows a replaceable solid center bit adapted to replace the center bit shown in Fig. 1;

Fig. 4 is a longitudinal sectional view showing in detail a special container for injecting cement suspension into the pilot bore, the container being iltted on the lower extremity of the inner barrel shown in Fig. 1; and

Figs. 5, 6, 7 and 8 are diagrammatic `views illustrating the several steps of the process.

Referring to the drawing, and more particularly to Fig. l, the rotary core drill assembly comprises a replaceable outer bit head I having ing carried on the hollow drill collar 3 which in turn carries the upper drill collar threaded at its upper end as at 5 to engage the usual string 'of drill pipe. At its lower end collar 4 is adapted to receive the driving collar 6 for driving the inner barrel. Within the hollow drill collar 3 is a retractable inner barrel 'I carrying at its lower end in threaded engagement va solid center bit head 8 to which is welded at its lowermost portion a drill point 9 of reduced diameter.

Ihe drill point 9` is approximately one inch in diameter and projects two or three inches below the lower extremity of the head 8 which is normally ilush with the lower cutting edges of the blade 2. In working position, the inner barrel 1v is placed in driving engagement with the driving collar 6 through the-driving dog IIJ connected to body member Il through the dog bolt I2. Body member II is in threaded engagement with the barrel 'I at its lower end while at its upper end it carries the head portion I3 having a spear head I4, a bifurcated lower portion I5 and stop collar I6. Connecting the bifurcated segments of the head member is pull bar pin I'l passing through the central slot in dog III and adapted to draw the dog I0 within the body member II against the force of spring 25, thus dieengaging the inner barrel 1 from the driving collar 6 when the spear head li is drawn upwardly. The center bit head 8 is adapted to be replaced by bit heads I8 or I9 shown in Figs. 2 and 3, respectively, or by container 20 shown in Fig. 4. Bit head I8 ,is provided at its lower extremity with cutting teeth 2|. Near the lower extremity on the inside of the bore a flexible core catcher 22 is carried in a recess 23. The head I8 is of such length that when the inner barrel 'I is in working position the cutter blades 2| project several inches below the cutting blades 2 of the outer drill. The solid bit head I 9 carries a wedge-shaped cutter 2l, the head I9 being of such length that the cutter 25 is ilush with blades 2 when the inner barrel is in working position.

As shown in Fig. 4, the container indicated generally at 20 is connected to the lower end of the retractable barrel 'I by means of a threaded coupling 26, centrally bored as at 21 and provided with a threaded closure plug 28 for purposes hereinafter described. Near the bottom of the cylindrical container 20 the bore thereof is reduced in diameter providing a shoulder 29. Closely fitting and slidable. in the small bore at 4the base of cylinder 2U is a piston member 30 seal with the shoulder 29 of the container while the outlet of bore 34 is sealed 'by the close fitting v walls in the base container 20. A helical com pression spring 35 is held in place in container 20 by the internal shoulders 36 on the coupling 26 and exerts its force against the upper side of piston head 3| tending to keep the piston 30 in its lowermost position as shown in Fig. 4. At its lower extremity, piston member 30 carries in threaded engagement a base 31 of enlarged diameter adapted to bridge the pilot hole 38 and thus prevent downward progress of the piston beyond the lower extremity of the well bore 39.

Head Il is bored centrallyas at 4I 'and 4I to provide openings in registry with bore 32. Lateral channels l2 extend from bore Il to the exterior of the head. As shown, container 28 may be fllled` with a fluid suspension of quick setting cement such as a thin slurry oi neat Portland cement containing magnetite, or some other suitable fiuid suspension of magnetically susceptible particles. If a Portland cement suspension is employed, the initial settingtime may be suitably adjusted if necsary by the addition of known accelerators or retarders so that the initial set takes place shortly after injection into the rock.

In operation, the apparatus described may be used in carrying out the invention in the following manner:

The bore is begun bythe usual rotary method, the bit head I9u being used in the central barrel until such time as it is desired to take a core sample by the .method of the invention. At such time an overshot (not shown) is loweredon a wire line through the hollow drill stem until it engages the spear head Il of the -inner barrel assembly. The inner barrel 1 is then retracted on the wire line, the upward motion of the pin I'i serving to retract the dog I0 and free the inner barrel from engagement with the outer barrel. At the surface of the well the solid central drill bit I9 is replaced with the drill head 8 and the inner barrel is again introduced into the drill pipe. The string of drill pipe is raised sufilciently to allow the dog to pass the driving collar 6 when the inner barrel reaches the bottom of the drill pipe and then the inner barrel and associated mechanism'is lowered through the drill pipe where it comes to rest on the bottom of. the hole with the driving dog I0 in extended position. 'I'he drill pipe is then lowered to bring the driving collar B intoengagement with dog i0 and rotated until the small bit has progressed downwardlyfor itscompletelength forming the pilot hole 3B' asshown in Figs. 4 and 6. ThenI the inner barrel is again retracted` as .before and the head 8 is removed.

A suspension is then made of extremely small magnetite particles in a slurry of quick setting cement. Coupling 26 and container v2li with asso` ciated mechanism being connected as shown'in Fig. 5, the closure 28 is removed and container 20 illled with the suspension by submerging bore 21,

then forcing piston 30 into cylinder 2li against the force of spring and allowing the spring to return the piston to the position'shown. thereby nlling the container. Closure 28 is then screwed into place and the coupling 26 is joined to the end ot barrel l.

The drill pipe is raised about three Afeet so that `the container to be subsequently introduced will project below the bit head, and the barrel lis then lowered into the we ll on a wire line through the -drill pipe, the tension on the. `head member I3 keeping the dog Il within its recess. As `shown in Fig. 4, when the bottom is reached. the base $1- of container 2li will extend aboutthree feet below the extremity of the drill bit 2, the wire line running slack andthe dog Il being pushed from its recess by ther spring 25. The drill pipe is thenlowered, causing driving collar i to ensue dog I0. As the weight of the drilll pipe is brought to bear on the'base 31 o! `container 2l through the inner'. barrel 4'|, piston 2li is fordupward cement suspension 4l being forced" thereby through passageways 3l, I2, Il. and li .into the against the force of spring II. the

not Vhole u previously armed by 4the w01 a.' Any excess of cement ilows laterally outward through ports l2.

Immediately after injecting the cement the outer string! is raised about ten feet to prevent` distortion of the earths field in the immediate locality qi the pilot hole 2l. After raising the outer string 4 either one of two procedures may be followed-depending on the character oi the 1 formation from which the sample is to be taken.

Ordinarily, I find it advantageous to remove both the -inner barrel and the outer barrel from the weiland replace the outer barrel shown with .a standard coring device (not shown) adapted to take va core ct large diameter, say, about three inches. In formations which are not well consolidated it is practically essential to take a core of this size Vin order to prevent the core from disintegrating.

After allowing sumcient time for the cement to set. the-formation is cored in the usual manner and, as s lio'wnv in Fig. 8, the core sample contains a plug of magnetic material 43 which is polarized in the direction of the earths magnetic field.

When the formation from which the sample is to be taken consists of a well consolidated and.y

not easily friable rock, the above procedure can be simplitled somewhat by operating in the following manner.

. InsteadT of boring the pilot holewith the drill bit 9' as shown in Fig..l, a drill head having .a smaller diameter bit, say one of` about one-half inch diameter, is substituted. After drilling `the pilot hole (which is correspondingly smaller than that shown in Figs. 4 and 6) the same procedure is used to inject the magnetic suspension therein and the inner barrel assembly is withdrawn on the wire line. The container 2l may then be reiplaced by the core bit I8 shown in Eig. 2, after which the inn e'r barrel 1 and associated parts are dropped through the drill pipe after raising the outer string l sufliciently to allow the dog `I0 f described -is best suited for use in well consolidated rocks. It has the advantage of obviating the necessity for removing the outer string 4 when the .core is to be'taken.

As before stated, in orienting the core sample recovered'according to the present invention it mayl 4be -brought close" to a sensitivev magnetic needle, the direction of its magnetization deter- 'mined and marked on the core. Thev direction 'ci the earths magnetic neld at the location or the `b o're beingj known, the core may then be oriented by pointing the marker in that direction. with,

the core ioriented, the strike. or the direction of dip (thedircction at right angles to the strike), of the bedding planes may be pre cisely determined.

wlfigs. 5 to. 8 illustrate the conditions at the corlng level during the several steps ot the process.' views are vertical sections of the rock taken netic meridian, that is, a vertical plane running ses` :soI

along' a plane including the earth's magnorth and south (magnetic north and south). i

The vector arrow in Fig. 8 indicates the direction of the earth's field; the vector in the general case being inclined with respect tohorisontal, as

'mmandorineunationvsmnrwittnecm- 'nlv 2,140,097.-Vt'ctor V. Vacguz'er, Oalmont, Pa.

tion, before or after its introduction into netic) latitude of the locality. Fig. 5 shows the bore bottom 39, in inclined strata. indicated at 60. Fig. 6 shows the bottom after the pilot hole 38 is formed, and Fig. 7 shows the hole filled with a plug of iiuent suspension (6I) of magnetic particles as described. Fig. 8 shows the rock core 62 cut by the core drill, in place, just before it is broken off (e. g. at 63) in known ways and raised to the surface. The ma'gnetite, etc. particles of the solidified plug are permanently oriented in alinement with the direction of the earths magnetic eld, as indicated schematically in the iigure, and on withdrawing the core to the surface, it is sufficient to determine the polarity of the plug, to nd how the core was originally. oriented; the direction of the earths magnetic field for the locality being known from other data. Even if the core drill was out of plumb when the sample was taken, the measurements are not vitiated.

The invention has been described in connection with oil well drilling, but it can, of course, be used in makin;r geological surveys in other fields.

While the invention has been specifically described in connection with various apparatus, the invention is not to be considered as limited thereby; the scope of the invention being characterized by the following claims.

What I claim is:

l. In the art of rock sampling during deep' drilling, the improvement which 'comprises the steps of introducing into the rock to be sampled a body of ferro-magnetic particles in such a state as to be susceptible of polar orientation under the influence of the earths magnetic field, allowing said particles to become so oriented and xing the particles to the rock while so oriented, and removing a sample of rock containing the fixed particles, thereby providing a, magnetic index by means of which the original position of the sample in the earth can be determined after removal..

2. In the art of rock sampling duringl deep drilling, the improvement which comprises the steps of introducing contiguously to the rock to be sampled a body of ferro-magnetic particles in such a state as to be susceptible of polar orientation under the influence of the earths magnetic eld, allowing said particles to become so oriented in the absence of forces which distort the earths field in the immediate locality o f said particles, fixing the space relationship between the particles while so oriented and the rock to be sampled and removing a sample of the rock together with said particles without varying said fixed space relationship.

3. In the art of rock sampling during deep drilling, the improvement which comprises in.-A

troducing into the rock. to be sampled a body of tiny ferro-magnetic particles in fluid suspension capable of adhering to rock, said suspension being adapted to set a relatively short time after said introduction and allowing the suspension to set in the absence of forces which distort the earths eld in the locality of said suspension.

4. In the art of rock sampling during deep drilling, the improvement which comprises boring a pilot hole in the rock to be sampled, introducing into said pilot hole a suspension of tiny ferromagnetic particles in fluid cement and allowing the cement suspension to set in cemented relation to the rock and in the absence of forces that distort the earths magnetic field in the immediate locality of the pilot hole, whereby the prospective sample is provided with a remanent magnetization in the direction of the earths leld.

5. In the art of taking and orienting rock samples, a method which comprises introducing contiguously to .the prospective rock sample a body of ferro-.magnetic particles in such a state as to be adapted to become oriented under the influence of the earths magnetic field, allowing said particles to become s oriented in the ab sence of forces which distort the earths magnetic eld in the immediate vicinity of the prospective sample, fixing the relationship between said particles while so oriented and said prospective sample, removing said sample together with said particles without varying their fixed relationship and determining the direction of remanent magnetization in said particles, whereby an index is afforded of the original position of said sample in the earth.

6. A method of taking rock core samples which comprises introducing into the rock to be cored a charge of magnetically susceptible material in a condition temporarily capable of polar orientation under the influence of the earths magnetic field, allowing such orientation to take place and become fixed, and removing a core sample of the rock containing said materials.

7. A method of taking rock core samples in wells which comprises drilling a small hole4 in the rock at the well bottom, introducing directly into the hole a body of minute ferro-magnetic particles suspended in a temporarily fluent cement capable of setting in time with the particles oriented parallel to the earths magnetic field, and taking a core sample from the. well bottom including said set body of particles cemented in place in the rock, whereby orientation of the core can be determined by observation of the magnetic properties of the core sample containing the cemented particles.

VICTOR V. VACQUIER.

DISCLAIMER ROCK SAMPLING METHOD. Patent dated December 13, 1938. Disclaimer led May 17, 1940, by the assignee, Gulf Research Development Company. Hereby disclaims from said patent, claims 1, 2, 3, and 5, and disclaims from claim 6 any interpretation thereof wherein the charge of magnetically susceptlble material introduced into the rock is vnot put temporarily into a non-magnetlc condi- [Ocial Gazette June 18, 1940.]

the rock. 

